It is a cool deal but I wonder what the life would be of one of these batteries.
Near the end of the article it points out that the expected life is in the 20,000 cycle range (vs. 400 for normal lithium ions). At one cycle a day that's nearly 55 years.
Unless there's some other breakdown mechanism that kills 'em over some shorter time, makes them leak too much charge, or randomly catch fire, explode, or leak toxics in unavoidable conditions, they could be very good.
(Possibly TOO good - like Nickel-Irons: If you only need to buy 'em once demand tapers off and the companies stop making them.)
What makes me optimistic is that charge time: Six seconds from minimum to full is just the sort of charge rate you need for regenerative braking in a car. So you could get rid of the supercapacitors and just use the ultralight main batteries.
Also: That kind of charge time means very low losses. (Otherwise they'd explode or melt.) Another plus.
